1. Field of the Invention
The present invention relates to a cap for use in liquid cartridge for reserving a liquid to be supplied to a recording device of an ink-jet recording apparatus and to a liquid cartridge having the same.
2. Brief Description of the Related Art
A liquid which is employed as a recording liquid for use in ink-jet recording apparatus is reserved in a liquid reservoir for reserving a liquid. In an ordinary ink-jet recording apparatus, the liquid cartridge is formed to be detachable from the apparatus and equipped with a feeding port for feeding the liquid. The liquid cartridge prior to exchange is in general sealed with the cap etc. to prevent a leakage of the liquid.
Some of co-inventors of the present invention have proposed in the Japanese Laid-open Patent Application Numbered: 10-291326 (1998) a highly air-tight liquid reserving cartridge having a cap for sealing the feeding port which is provided on such a liquid cartridge without any creep deformation phenomena of the cap. The liquid reserving cartridge and the cap disclosed in the Laid-open Application mentioned above are illustrated in FIG. 8 (PRIOR ART).
In the conventional liquid reserving cartridge as shown in FIG. 8, the liquid reserving cartridge 101 serving as the liquid reservoir for reserving the liquid is provided with the feeding port 102. The cap 103 for closing up aforesaid feeding port 102 is fixed onto the cartridge 101 and the liquid cartridge 101 for reserving the liquid is sealed up by an elastic member 104 which is disposed on a plane to be contacted with the feeding port 102 of the liquid cartridge 101.
In the cap for use in liquid cartridge as mentioned above, the cap 103 is turned around during unsealing of the sealed liquid cartridge 101 thereby to shear off a welding portion 105, which removes the cap 103 from the liquid cartridge 101. As a method of fixing the cap 103 onto the liquid cartridge 101, a plurality of the welding portions 105 are first formed on a periphery of a cylindrical portion of the cap 103, which is used to encapsulate the feeding port 102, so as to protrude toward the liquid reserving cartridge 101 thereby to contact each of the welding portions 105 with the liquid cartridge 101 to fuse contacted planes between the welding portions 105 and the liquid cartridge 101 to be welded with each other by a use of an ultrasonic welding technology.
The ultrasonic welding technology is in general a sort of technologies wherein an ultrasonic vibration propagating body (referred to as "welding horn" hereinafter) contacts a member to have aforesaid member vibrate at a high frequency, friction heat of which fuses plastic resin-made welding portions thereby to be fixed. The ultrasonic vibration exhibits a larger amplitude at a portion of the member which is more adjacent to the welding horn while the amplitude is reduced more as the portion goes apart from the welding horn because of an inner loss induced in the member, which makes it difficult to attain a desirable welding energy. A distance which the ultrasonic vibration propagates effectively is regarded in general as from 4 to 5 millimeters (referred to as "mm" hereinafter) in a case when the member is formed of a crystalline plastic resin such as a polypropylene polymer.
However, since the conventional example mentioned above has to have contact the welding horn, which serves for fusing the welding portions 105 and the liquid cartridge 101 to each other, orthogonally with respect to the cylindrical portion of the cap 103 the separates the welding portions 105 remotely more than 5 mm from the welding horn dependently upon shapes of the cartridge and the cap, it hinders an effective propagation of the ultrasonic vibration, resulting in an dissatisfactory welding. To complement the dissatisfactory welding results, it is necessary to provide from 6 to 8 welding portions.
On the other hand, a necessity of providing a stronger ultrasonic vibration induces a fusion between the elastic member 104 and the feeding port 102 which are located adjacently to the welding horn, corresponding to the shapes of the cartridge and the cap. The fusion between the elastic member and the feeding port has a danger that it produces inadequacies such as an increase in operational force during opening and closing the cap 101, a deformation of the feeding port 102 etc. Furthermore, to provide the stronger vibration as mentioned above shortens a service lifetime of the welding horn, which invites an increase in manufacturing cost of the liquid cartridge.